Thermostatic selective heating, cooling, and circulating interlocking control system



- R. W. QLSEN THERMOSTATIC SELECTIVE HEATING, COOLING, AND

A ril 3, 1951 2,547,657

' CIRCULATI-NG INTERLOCKING CONTROL SYSTEM Filed Oct. 30, 1947 2 Sheets-Sheet 1 inventor. Ron-aid W. Olsen,

His Attor vfi ey.

vby 294M; M

April 1951 R. w. OLSEN 2,547,657

THERMOSTATIC SELECTIVE HEATING, COOLING, AND

CIRCULATING INTERLOCKING CONTROL SYSTEM Filed Oct. 50, 1947 2 Sheets-Sheet 2 Ronald Olsen, by KM rm His Attorney.

Patented Apr. 3, 1951 THERMOSTA'IIC SELECTIVE HEATING,

COOLING, AND CIRCULATING INTER- LOCKING CONTROL SYSTEM Ronald W. Olsen, Caldwell, N. J., assignor to General Electric Company, a corporation of New York Application October 30, 1947, Serial No. 783,054

6 Claims.

The invention relates to thermostatic selective heating and cooling temperature control systems involving a circulating heating and cooling medium and particularly to central plant year-round air conditioning systems having air heating, cool- .ing and circulating elements separately operatable under thermostatic selective control. The invention provides thermostatic selective intermittent-continuous circulation interlocking control improvements that may be used with other heating and cooling temperature control systems and with electric or pneumatic control as desired.

The principal object is to provide an improved thermostatic selective interlocking control system for producing intermittent circulation of the air or other heat exchange medium jointly with the heating thereof to meet heating demands and continuous circulation of the air or other medium with intermittent cooling thereof to meet cooling demands.

Another object is to provide a heat exchange medium and space temperature responsive dual thermostatic interlocking control for starting operation of the heat exchange medium circulator upon operation of either the heater for the medium or the cooler for the medium while maintaining continuous operation of the circulator after any operation of the cooler until a subsequent operation of the heater occurs.

Another object is to provide an improved selfholding interlocking control relay system for automatically and sequentially interlocking a thermostatic heat exchange medium circulator control with a heater and cooler. selective starting and stopping thermostatic control so that the circulator will be operated when the medium becomes heated upon each operation of the heater but upon starting operation of the cooler the circulator automatically is maintained continuously in operation until a subsequent starting of the heater.

The improved interlocked thermostatic selective control system is particularly advantageous for a year-round air conditioning system since it insures that during the heating season the air circulator does not run untilthe air is effectively heated thus avoiding cold drafts and also providing some reduction in the circulator operating costs while during the cooling season the air circulator will be run continuously to provide the benefit of the additional comfort obtained by constant air .movement.

Further objects and advantages of the invention will appear in the following description of the accompanying drawing in which Fig. 1 schematically shows a central plant year-round electrically controlled air conditioning system embodying the thermostatic interlocking improvements of the present invention in a preferred form; Fig. 2' is a partial View showing a modified form of room temperature responsive thermostat that can be used in the control system shown in Fig. 1; and Fig. 3 schematically shows the invention embodied in a pneumatic control system for a central plant year-round air conditioning system such as shown in Fig. 1.

In the year-round air conditioning system shown in Fig. 1, the temperature of the space Ii] is controlled by circulation of the air from the space through the duct ll into the central plant year-round air conditioner [2 upon operation of the air circulator or blower l3 with the heated or cooled air returned to the space H) through the duct [4. Fresh air may be admitted to the system through the fresh air duct 15 under the control of the proportioning dampers l6 and H. The circulator or blower I3 is operated to circulate air from the space Ill through the air conditioner 12 upon energization of the electric motor I8 that drives the air circulator l3.

The air conditioner I2 is shown as provided with a conventional cooler l9 comprising the fin tube evaporative heat exchanger 20 connected by return line 2| with the refrigerant gas compressor 22 that supplies the refrigerant through pipe 23 to the condenser 2c and thence to the liquid receiver 25. The flow of liquid refrigerant in the line 26 to the evaporative heat exchanger 20 is controlled by the thermostatically operated flow regulating valve 21 having the bulb 28 responsive to the temperature of the gas return line 2 l. The compressor 22 is operated to cool the air circulating through the air conditioner 12 upon energization of the electric motor 29 that drives compressor 22.

The air conditioner 12 also is shown provided with a conventional air heater 30 comprising the air heating coil 3| to which steam or hot water may be supplied through pipe 32 from the boiler furnace 33 having the return line 34 connected to the other end ofcoil 3|. furnace 33 is provided with suitable automatic firing means forstarting the furnace into operation 'to heat the air in the conditioner 12, such means being illustrated schematically as an automatic oil burner 35.

The air conditioner 12 also may be provided I with a suitable humidifier 38 illustrated sche- The boiler heating value.

plied to the drip pan 39 through pipe 40 under the control of the electromagnetically operated valve 4| with the water passing through perforations in the bottom of pan 39 over the humidifying screens 42 located in the path of the air flow. The excess water collected by the pan 43 is discharged to the drain 44.

Selective operation of the air cooler I9 for cooling the air and the air heater 30 for heating the air is controlled by thermostatic means 45 responsive to corresponding variations in the temperature of the air in the space It] in different temperature ranges. As schematically shown in Fig. 1 a conventional adjustable .heating control thermostat and a conventional adjustable cooling control thermostat 5| may be used although it will be understood that a suitable single blade combined heating and cooling selective thermostat 45 such as shown in Fig. 2 with separately adjustable contacts 4'! and 48 may be used if desired.

The heating control thermostat 50 of Fig. 1 controls the energization of the heating control switching relay 52 from the secondary 53 of a transformer having its primary winding 54 continuously energized from the supply lines L|, L2 with the energizing circuit extending through conductors 55 and 56. The cooling control thermostat 5| similarl controls the energize.- tion of the cooling control switching relay 51. It will be understood that the cooling control thermostat 5| may normally be set to energize relay 5'! when the temperature in space ID 'increases above a desired value, for example 80 F., while the heating control thermostat 56 may be set to energize relay 52 when the temperature of space It falls below a different desired value, for example 72 F. Thus the selective heating and cooling starting and stopping of the air conditioner l2 will normally occur in different temperature ranges.

The heating control switching relay 52 is provided with a normally open heating circuit controlling contact 60 that closes upon energization of the relay to energize the burner motor 35 from the supply lines Ll, L2 through the conductors BI, 62. Relay 52 also is provided with the normally closed interlocking contact 63 and the normally open interlocking contact 64 that cooperate with the self-holding interlocking switching relay 15 in selectively controlling the intermittent-continuous operation of the blower driving motor It as more fully described hereinafter.

The cooling control switching relay 5! is provided with a normally open cooling circuit controlling contact 66 that is closed upon energization of the relay to complete an energizing circuit for the compressor driving motor 29 from the supply lines LI, L2 through the conductors 61, 68. Relay 5'! also is provided with a normally open interlocking contact 69 that cooperates with relay 75 in controlling the operation of the blower driving motor l3.

During heating operation of the air conditioner I2, the intermittent operation of the blower driving motor I8 is jointly controlled by the heating control thermostat 56 and a cooperating interlocking thermostat 12 that is responsive to the temperature of the air in the air conditioner l2. Interlocking thermostat I2 engages with contact 13 when the air is cold or below its normal heating value and With the contact 14 when the air is heated to its normal This normal heating value is in the neighborhood of F. to F. During cooling operation of the air conditioner l2, the starting into operation of blower motor I8 is under the joint control of cooling thermostat 5| and the interlocking thermostat 12 in its cold position but continued operation of the blower is independently maintained by the self-holding interlocking relay 15 until heating operation subsequently occurs.

Operation of Fig. 1

If the temperature in space It] falls so that heating thermostat 50 closes its contacts, relay 52 is energized to close contact 60 and thereby start operation of the boiler furnace 33 to supply heating medium to the coil 3| and then heat the air in the air conditioner I2. At the same time the normally open interlocking contact 64 is closed and the normally closed interlocking contact 63 is opened. As soon as the operation of the boiler furnace 33 has become effective to heat the air in the conditioner l2, interlocking thermostat 12 will respond to engage with contact 14. This completes an energizing circuit for the blower motor [8 extending from supply line L| through conductor 80, contact 64, conductor 8|, contact 14, interlocking thermostat l2, conductors 82 and 83, blower driving motor l8 and conductor 34 to the other supply line L2. As a result, blower I3 is started into operation to circulate air from the space I0 through air conditioner l2 to be heated by the heating coil 3| and thus effect a transfer of heat to the space I 0 to meet the heating demands. When the transfer of heat to space l0 becomes suificient to raise the temperature above the desired value, thermostat 50 opens its contacts to deenergize relay 52 and thereby stop operation of both the furnace operating burner motor 35 and the blower driving motor l8. Thus during heating operation of the air conditioner |2 the air circulator is operated jointly with the air heater and the operation is intermittent in accordance with the heating demands.

If the temperature in "space It) increases so that the cooling control thermostat 5| closes its contacts, then relay 5'! is energized and closes its normally open contact 66 to start operation of the compressor driving motor 29 to supply cooling refrigerant to cool the air passing through heat exchanger 20 in the air conditioner I2. Under such temperature conditions the interlocking thermostat 12 will normally engage with its cold contact 13. Hence when the interlocking contact 69 of cooling relay 5'! closes, an energizing circuit for operating the blower driving motor I8 jointly with the air cooler will be established extending from the supply line Ll through conductor 85, the normally'closed contact 63 of heating control relay 52, conductor 86, contact 69, conductor 81, conductor 88, contact 13, interlocking thermostat l2, conductors 82 and 83, the blower driving motor H3 and conductor 84 to supply line L2. As soon as interlocking contact 69 is closed, the interlocking relay 15 becomes energized with the energizing circuit therefor extending from the supply line Ll through conductor 85, the normally closed contact 63 of the heating control relay 52, conductor 86, contact 69, conductor '81, the operating winding of relay l5 and conductor 89 to supply line L2. Upon the resulting response of relay 15, its'normally open self holding contact 76 is closed so as to maintain relay 75 energized through conductor 98 that shunts the cooling relay contact 69. This shunt circuit through interlocking relay selfholding contact I6 insures that the blower driving motor I8 is maintained energized continuously even though the cooling control thermostat 5i responds to the cooling action of the refrigerating compressor operation and deenergizes relay 51 and thereby opens contact 69. In fact, when interlocking relay I5 once becomes energized, due to energization of the cooling control relay 51, the only waythat it can be deenergized byby a subsequent operation of the heating control relay 52 so as to open its interlocking contact 63. In this way the self-holding interlocking relay I5 insures continuous operation of the air circulator is upon operation of the cooler I9 until a subsequent operation of the heater 30 is required.

As schematically shown in Fig. 1, the interlocking relay I5 also is provided with a normally closed contact 'I! that serves to open the primary of the control transformer and thereby prevent the humidostat 78 that is responsive to the humidity of the air in the space I!) from energizing the operating electromagnet I9 and the water control valve ill of the humidifier 38 during cooling operation of the air conditioner I2. The energizing circuit for the humidifier operating electromagnet 19 extends through conductors 95, 96 and 3?.

While the automatically fired boiler furnace 33 has been schematically illustrated in Fig. 1 for supplying heating medium to the heat exchanger coil 3 I, it will be understood that a suitable electrically operated steam or water flow control valve may be used in place of the furnace 33 if desired.

With the pneumatic control system embodying the invention shown in Fig. 3, selective heating and cooling is initiated under the control of the heating control thermostat WI and the cooling control thermostat I62, each of which may be of conventional form adapted to admit pressure from a suitable source I03 to the several pneumatically operated devices controlled thereby. Thus when heating is required, the heating control thermostat IGI admits pressure through tubes HM and I65 to the operating bellows I06 that closes the normally open contact I! to start operation of the burner mechanism 35 of the furnace 33. The burner mechanism 35 is shown connected through the conductors I08 and I09 to be energized from the electrical supply lines LI, L2 upon closure of the pneumatically operated, normally open, contact I07.

Similarly the blower motor I8 is shown connected by conductors l I2 and I I3 to be energized from the supply lines LI, L2 upon closure of the normally open contact H4. Contact II4 is closed by the admission of pressure to the operating bellows M5 therefore under the control of the heat exchange thermostat II 6 that may be of the conventional type to admit air pressure from the tube II! to the tube I I8 when the air in the central plant air conditioner I2 is heated to a desired temperature value, for example, 130 or 140. Thus, the driving motor I8 or blower I8 can not be energized during heating operation of the air conditioner until the furnace 33 has been set into operation to supply heating medium to the air heater 3% and effectively raise the temperature of the air to a value that will not result in circulating objectionably cool air in the space I0. During heating operating air pressure may be admitted by the humidostat I from tube I04 to tube I22 in order to expand the operating bellows E23 and thereby admit water through valve I24 to the air humidifier 38 as required to maintain desired humidity conditions.

Whenever air pressure is admitted to the furnace starting operating bellows I03; at the same time air pressure is supplied through pipe I26 to the right hand side of the interlocking diaphragm I2! having its periphery changed in the split casing I28 and connected by means of the operating rod I29 with the lever I33 that is pivoted at its lower end on the pivot pin I3I. The upper end of lever I38 is connected by the over-center spring I32 to the knee of the toggle levers I33 that serve to open and close the interlocking blower control contact I33. Thus with pressure always exerted upon the righthand side of diaphragm l2! during heating operation, lever I30 will carry spring I32 over the center pivot I35 of the toggle lever and thereby bias the toggle levers l33 to buckle into engagement with the stop I36 and thereby always open contact I34 that is connected by conductors I31 and I38 in shunt with the pneumatically operating switch contact II4.

Thus as soon as heating operation is started, the energization of the blower driving motor I3 is always placed under the control of the pneumatically operated contact IIfi that is closed under the control of the heat exchange thermostat I IS. Also whenever heating is initiated and contact I34 is opened by the admission of pressure on the right hand side of diaphragm I21, the over center spring and toggle interlocking mechanism is such that the contact I34 will remain in the open position even though the pressure is removed from the right hand side of diaphragm I21 until pressure is admitted to the lefthand side of the diaphragm I21 during'cooling operation as described below.

During cooling operation, the cooling control thermostat I32 admits pressure from the source E33 through tube I40 to tube I4I thereby expanding bellows I42 to close contact I43 and thereby energizes the driving motor 29 for compressor 22 with the energizing circuit extending from the supply lines LI and L2 through conductors I44 and I45. At the same time, air pressure is admitted to the left hand side of the diaphragm I2 1. In this case, the diaphragm I21 operates through arm I29 to move lever I351 to the right and thereby carry the operating spring I32 over the center pivot I35 of the toggle operating arm I33. As a result the toggle arms I33 are moved out of engagement with stop I33 and straightened so as to close with switch contact I34 and thereby energize the blower driving motor I3 through conductors H2 and II3 so as to start operation of the air circulator 53 substantially at the same time that compressor 22 is started into operation.

When the operation of compressor 22 produces sufiicient cooling of the air circulated from the central plant air conditioner I2 by the air circulator I3 into the space M, then the cooling thermostat I32 will respond to cut ofi the air pressure from the operating bellows I 42. As a result, contact I43 will be returned to its normally open position, thereby deenergizing the compressor driving motor 29. At the same time the pressure is relieved from the left hand side of the diaphragm I21 and lever I30 is returned to its mid-position in which it is shown. However, in this case spring I32 will not be moved over the central pivot I35 of the toggle levers I33 and consequently the toggle lever I33 will remain in engagement with stop I35 and thereby maintain contact I34 in its circuit closing position to maintain motor l8 energized and thus continue 7 the :o'perati'ohzof :theair circulator 13 even though the compressor 32 is shut down. The over cen- --ter spring and :toggle arrangement is such that when .once straightened so as to close contact 1:34 to operate the air circulator I3 during cooling operation, the air .circulator will be maintained .in .continuous operation thereafter until a subsequent heating operation is produced under the control of the heating control thermostat 1101 so as to admit pressure to the right-hand .side of diaphragm l2! and thereby return the over center spring I32 and the toggle levers I33 to their respective positions shown in Fig. 3.

Thus the pneumatic system shown in Fig. 3 provides intermittent operation of the air circulator 13 along with the heating of the air during the heating season and continuous operation of the air circulator 13 with intermittent operation of the compressor 22 during the cooling season. In this way the added benefit of the cooling effect resulting from the continuous air circulation is made available selectively during the heating season without the chance for circulating cooling drafts in space H) during the heating season.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric control for a heating, cooling and circulating system having in combination .a heating circuit, a cooling circuit, thermostatic switching means selectively to close and open said circuits intermittently upon corresponding temperature variations, a circulation circuit having interlocking switching means to close said circulation circuit upon closure of said heating and cooling circuits, and circuit control means including a self-holding electroresponsive switching device controlled by said thermostatic switching means to maintain said circulation circuit closed after closure of said cooling circuit until a subsequent closure of said heating circuit.

2. An electric control for a heating, cooling and circulating system having in combination a heating circuit, a cooling circuit, a first thermostatic switching means selectively to close and open said circuits intermittently upon corresponding temperature variations, a circulation circuit having a second thermostatic switching means to close said circulation circuit after closure of .said heating circuit, and circuit control means including a self-holding electroresponsive switching device controlled by said first thermostatic switching means to close said circulation circuit upon closure of said cooling circuit and maintain said circulation circuit closed until a subsequent closure of said heating circuit.

3. An electrical control for a heating, cooling and circulating system having in combination thermostatic switching means having heating and cooling circuits alternatively closed thereby, and a circulation circuit controlling relay having an energizing circuit including a pair of contacts closed by said thermostatic switching means upon closure of said cooling circuit and a self-closing holding circuit around said contacts opened by said thermostatic switching means upon closure of said heating circuit.

4. A pneumatic control for a heating, cooling and circulating system having in combination selective thermostatic valve means, pressure responsive heating and cooling, starting and stopping control elements selectively controlled therebyin response to corresponding temperature variations, and circulation starting and stopping control means having pressure responsive operating means under control of said selective thermostatic valve means for starting circulation upon starting operation of said cooling control element and stopping circulation only upon starting operation of said heating control element.

5. A temperature control system having in combination, a circulatorfor a heating and cooling medium, means for heating said medium, means for cooling said medium, a first thermostatic control means for selectively operating said heating means in accordance with temperature variations in a predetermined heating range, a second thermostatic control means for selectively operating said cooling means in accordance with temperature variations in a predetermined cooling range, circuit means including two alternate paths in parallel for supplying energy to said circulator, a first circulator actuating means including a switch in one of said paths and actuated by said first control means for operating said circulator intermittently during said heating range, a second circulator actuating means including a switch in the other of said paths for maintaining said circuit means closed during said cooling range for operating said circulator continuously, and means dependent upon actuation of said first thermostatic control means upon a demand for heating for rendering ineffective said second circulator actuating means.

6. A temperature control system having in combination, a circulatorfor a heat transfer medium, means for heating said medium, means for cooling said medium, a first thermostatic control means for selectively operating said heating means inaccordance with temperature variations in a predetermined heating range, a second thermostatic control means for selectivel operating said cooling means in accordance with temperature variations in a predetermined cooling range, circuit means including two alternate paths in parallel for supplying energy to said ond switch closed during said cooling range to operate said circulator continuously, and means under the control of said first control means for opening said second switch upon a call for heating.

RONALD W. OLSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,137,833 Crago Nov. 22, 1938 2,155,256 'Crago Apr. 18, 1939 

